What the three classes are
The IPC classes describe the service environment of the product, and they set the acceptance criteria that follow from it.
- Class 1 — general electronic products. The primary requirement is that the assembly functions. Cosmetic defects and some process imperfections are acceptable.
- Class 2 — dedicated service products. Continuous operation and a longer service life are expected; the assembly should be reliable but need not be perfect. This is the class most industrial, commercial and consumer boards are built to.
- Class 3 — high-reliability products. Failure is not acceptable, service is difficult or impossible, and the product may be safety-critical. Medical, aerospace and defence work typically lands here or is specified by the customer's own standard.
What actually changes on the board
The class does not change the laminate or the copper. It changes what is accepted:
- Annular ring and registration. How much copper must remain around a hole, and how much misregistration is tolerated, tightens as the class rises.
- Plating and barrel quality. Void limits and minimum plating thickness in the hole wall are stricter.
- Solder mask and legend. Registration and coverage tolerances tighten; mask over pads becomes less tolerable.
- Inspection and documentation. More inspection, more coupons and more records — which is a large part of the cost difference.
- Assembly workmanship. Under IPC-A-610 / J-STD-001, fillet shape, wetting angle and void limits also tighten with class.
The effect on price is mostly yield. The process does not change dramatically; the number of boards that fail acceptance does.
Specifying it properly
Two standards are in play, and naming only "class 2" leaves it ambiguous:
- The bare board: IPC-6012 (rigid), with acceptability to IPC-A-600 — state the class here.
- The assembly: IPC-A-610 and J-STD-001 — state the class here too.
A drawing that says "Class 2" and nothing else will be interpreted by each supplier from its own default. A drawing that says "IPC-6012 Class 2, IPC-A-610 Class 2" cannot be misinterpreted.
Where the money is better spent
If a product is serviceable and a failure is recoverable, Class 2 plus a proper design review usually delivers more reliability per euro than Class 3.
The cases where Class 3 earns its cost are specific: a board that cannot be replaced, a failure that injures someone, or a qualification programme that requires it. In those cases the class is not a preference; it is part of the product definition.
Conversely, asking for Class 3 on a prototype to "be safe" raises cost and rejection rate without changing the design's real failure modes — those are found by testing the product, not by inspecting the board harder.
What to send
The Gerber set, the stack-up, the finish, the class for fabrication (IPC-6012) and for assembly (IPC-A-610), plus any customer-specific standard that overrides them — automotive programmes under IATF 16949:2016, for example, usually add their own requirements on top.
The published process limits are on the capability page; the standards behind the certificates are listed on the certificates page, and the difference between a bare board and an assembly is covered in the PCB vs PCBA note.
